Smooth degradable PETG film and preparation method thereof

Abstract

The invention relates to the technical field of PETG films, in particular to a smooth degradable PETG film and a preparation method thereof.The smooth degradable PETG film comprises an outer layer, a film body and an inner layer which are sequentially arranged, and the film body is formed by thermally coating a degradable polyester coating; the degradable polyester coating comprises the following raw materials in parts by weight: 40-60 parts of degradable polyester, 20-40 parts of PETG slices, 3-7 parts of a compatible dispersant, 4-8 parts of a flexibilizer, 5-10 parts of a plasticizer, 4-10 parts of a slipping agent, 10-20 parts of modified bamboo fibers, 5-10 parts of a filler and 1-5 parts of toluene diisocynate. The degradable PETG film provided by the invention overcomes the defects of existing products, and also has good biodegradability, good mechanical properties, good optical properties and good light aging resistance.

Description

Technical Field

[0001] The invention relates to the technical field of PETG films, and in particular to a smooth and degradable PETG film and a preparation method thereof. Background Art

[0002] PETG is a transparent plastic and a non-crystalline copolyester. The commonly used comonomer of PETG is 1,4-cyclohexanedimethanol (CHDM), the full name of which is polyethylene terephthalate-1,4-cyclohexanedimethanol. It is a product of terephthalic acid (TPA), ethylene glycol (EG) and 1,4-cyclohexanedimethanol (CHDM) by ester exchange polycondensation. Compared with PET, it has more 1,4-cyclohexanedimethanol comonomer. Therefore, the performance of PETG is very different from that of PET and PCT. It has outstanding thermoforming performance, toughness, weather resistance and excellent chemical resistance, and is environmentally friendly and economical. Its shortcomings are that at present, only Eastman in the United States and SK in South Korea have relatively mature technologies. The PETG used in China is all imported. Because of its high price, it is generally not used alone. It is mostly used as a surface heat-sealing layer of a three-layer composite or a two-layer composite. Its shortcomings are that the source of PETG slices is all imported, and the cost is too high. Summary of the invention

[0003] In order to overcome the shortcomings and deficiencies in the prior art, the object of the present invention is to provide a smooth and degradable PETG film, which overcomes the defects of existing products and also has good biodegradability, good mechanical properties, good optical properties and good light aging resistance.

[0004] The purpose of the present invention is to provide a method for preparing a smooth and degradable PETG film, which is simple and convenient, has low requirements on production equipment, is low in cost, is conducive to industrial production, and can effectively overcome the shortcomings of previous lithium-ion batteries.

[0005] The purpose of the present invention is achieved through the following technical scheme: a smooth and degradable PETG film, comprising an outer layer, a film body and an inner layer arranged in sequence, wherein the film body is formed by thermal coating of a degradable polyester coating; the degradable polyester coating comprises the following raw materials in parts by weight: 40-60 parts of degradable polyester, 20-40 parts of PETG slices, 3-7 parts of a compatible dispersant, 4-8 parts of a toughening agent, 5-10 parts of a plasticizer, 4-10 parts of a smoothing agent, 10-20 parts of modified bamboo fibers, 5-10 parts of a filler and 1-5 parts of toluene diisocyanate.

[0006] The degradable PETG film of the present invention overcomes the defects of existing products, and also has good biodegradability, good mechanical properties, good optical properties, and good light aging resistance; wherein the film body adopts a degradable polyester coating, so that the effect of the sheet obtained when the thickness of the PETG slice layer in the composite sheet is 8.3-16.1% can achieve the heat sealing performance and low-temperature processing effect of the sheet obtained when the thickness of the PETG slice layer is about 20%, reducing the amount of PETG slices and greatly reducing the production cost. The addition of a lubricant to the degradable polyester coating can effectively reduce the friction coefficient of the film surface, so that it has a smooth touch during use, such as in some packaging application scenarios, it is convenient to load and remove items, and can improve the convenience of user operation; the use of raw materials such as degradable polyester and modified bamboo fiber allows the film to be gradually degraded in a natural environment or under specific conditions after being discarded, reducing pollution to the environment and meeting environmental protection requirements. The addition of compatible dispersants can promote the uniform dispersion of raw materials with different polarities and properties in the coating system, ensuring that modified bamboo fiber, fillers, etc. are fully mixed with other raw materials to avoid agglomeration and other phenomena, thereby ensuring the uniformity of coating performance; while tougheners and plasticizers work synergistically with biodegradable polyester, PETG slices, etc. from the perspectives of enhancing toughness and improving flexibility, respectively, so that the final film can maintain a certain strength while having good processability and performance, and adapt to different application scenarios; the addition of lubricants plays an independent role in reducing the surface friction coefficient in the system, and together with other raw materials constitutes The film body and coating structure are coordinated to give the film a smooth surface property without affecting the overall performance; the modified bamboo fiber can be used as a reinforcing phase to improve the strength and other properties of the film on the one hand, and its degradable properties also help to improve the degradable performance of the entire film on the other hand, which echoes the environmental performance of raw materials such as degradable polyester; the filler can play a filling role, reducing costs, and according to the characteristics of the filler itself (such as hardness, thermal conductivity, etc.), it may also fine-tune certain properties of the film (such as wear resistance, thermal stability, etc.), and it cooperates well with other raw materials under the action of compatible dispersants.

[0007] Preferably, the degradable polyester is composed of at least one of polybutylene terephthalate succinate, polybutylene terephthalate adipate, polybutylene succinate-adipate, poly(butylene adipate-co-2,5-furandicarboxylate), poly(butylene succinate-co-2,5-furandicarboxylate) and polybutylene succinate-polylactic acid and at least one of polyglycolic acid, polylactic acid, polyglycolide-lactide and polyglycolide-caprolactone in a mass ratio of 0.8-1.2:0.6-10.

[0008] The degradable polyesters in the present invention are compounded according to the above dosage and are used together as the base resin of the biodegradable polyester composition; wherein polybutylene terephthalate succinate, polybutylene terephthalate adipate, polybutylene succinate-adipate, poly(butylene adipate-co-butylene 2,5-furandicarboxylate), poly(butylene succinate-co-butylene 2,5-furandicarboxylate) or polybutylene succinate-polylactic acid as polyester A can improve the toughness of the composition, and polyglycolic acid, polylactic acid, polyglycolide-lactide or polyglycolide-caprolactone as polyester B can improve the strength of the composition, so that the polyester composition has both high toughness and high strength, and can further improve the comprehensive performance of the prepared degradable polyester; furthermore, the degradable polyester and PETG slices, as the main basic raw materials, jointly construct the basic framework of the film body, provide a certain strength and toughness basis, and both have processability and can form a continuous film layer structure during the hot coating process.

[0009] Preferably, the PETG slices are one or a mixture of PETGCR-5511 and PETG CR-5531.

[0010] Preferably, the compatible dispersant is maleic anhydride copolymer microspheres.

[0011] Preferably, the toughening agent is composed of ethylene terephthalate, ethylene isophthalate, ethylene glycol, oxalic acid and stearate in a mass ratio of 3-5:0.1-0.3:1-3:1-3:0.04-0.08.

[0012] Preferably, the plasticizer is epoxidized soybean oil and / or pentaerythritol.

[0013] Preferably, the lubricant is at least one of erucic acid amide, ethylene bis stearamide, silica open lubricant masterbatch, paraffin, ethylene-vinyl acetate copolymer, and ethylene-acrylic acid copolymer.

[0014] Preferably, the modified bamboo fiber comprises the following raw materials in parts by weight: 4-8 parts of phthalic acid type unsaturated polyester resin, 1-5 parts of 1,6-hexamethylene diisocyanate, 30-60 parts of bamboo fiber, 5-10 parts of polyethylene grafted maleic anhydride, 1-5 parts of graphene oxide, and 1-3 parts of initiator; the initiator is N,N-dimethylaniline; The modified bamboo fiber is prepared by the following method: A1. Soak the bamboo fiber in a hydrogen peroxide solution with a mass fraction of 1.0-1.5%, adjust the pH value of the solution to 10-12, soak for a period of time, and then put it into a blast drying oven to obtain alkaline hydrogen peroxide pretreated bamboo fiber for standby use; A2. According to parts by weight, graphene oxide is prepared into a solution with a concentration of 0.1-0.4 mg / ml, and then polyethylene grafted maleic anhydride, initiator and 1,6-hexamethylene diisocyanate are mixed evenly, and then bamboo fiber is added to the mixed system and stirred evenly, vacuum heated to 90-140°C, and pressurized to 3.0-3.2 MPa, treated for 20-40 minutes, and finally transferred to a vacuum drying oven, heated to 130-140°C and dried for 3-7 hours to obtain modified bamboo fiber.

[0015] After the modification treatment in the present invention, the comprehensive performance of bamboo fiber is expected to be improved. For example, its mechanical properties such as strength and toughness may be improved, so that it can better withstand external forces when used as a material, expanding its application range; the modification process helps to improve the interface compatibility between bamboo fiber and other materials (such as polyester that may be composited with it), so that bamboo fiber can better combine with the matrix in the composite material system, thereby improving the overall performance of the composite material and reducing the performance degradation problem caused by interface incompatibility. Pretreatment principle in the preparation process (step A1): soak bamboo fiber in alkaline hydrogen peroxide solution. Hydrogen peroxide has certain oxidizing properties under alkaline conditions (pH value is 10-12), which can oxidize the surface of bamboo fiber to remove some impurities and wax on the surface. At the same time, some active functional groups (such as hydroxyl groups) may be introduced on the fiber surface to clean and preliminarily activate the fiber surface, laying the foundation for subsequent modification treatment; modification treatment principle (step A2): prepare graphene oxide into a solution of a certain concentration so that it can be evenly mixed with other raw materials and act on bamboo fiber. Graphene oxide has excellent mechanical properties, electrical properties, etc., and can give bamboo fiber new performance characteristics through compounding with bamboo fiber; polyethylene is grafted with maleic anhydride, initiator and 1,6 -Hexanediocyanate is mixed with bamboo fiber and stirred evenly, and then reacted under vacuum, heating and pressure conditions. Polyethylene grafted maleic anhydride can introduce specific functional groups on the surface of bamboo fiber through grafting reaction to improve the surface properties of bamboo fiber; initiator can trigger related polymerization reactions, etc., to promote chemical reactions between various raw materials; 1,6-hexamethylene diisocyanate can react with active functional groups on the surface of bamboo fiber and functional groups in other raw materials to form chemical bonds and other connections, further enhancing the modification effect of bamboo fiber. Finally, vacuum drying is used to further solidify the modification effect and remove impurities such as moisture. Specific surface oxidation reaction (A1): In alkaline hydrogen peroxide solution, the active oxygen species (such as hydroxyl radicals, etc.) produced by the decomposition of hydrogen peroxide can react with the organic matter on the surface of bamboo fiber to form an oxidation reaction. The reaction equation can be roughly expressed as (taking an organic matter R on the fiber surface as an example): R + [O] (from the decomposition of hydrogen peroxide) → oxidation product. This process achieves the initial modification of the bamboo fiber surface and produces more active sites for subsequent reactions; Grafting and cross-linking reaction (A2): Under the action of the initiator, the double bonds in the polyethylene grafted maleic anhydride molecules can be opened, and then grafted with the active functional groups (such as hydroxyl groups, etc.) produced after pretreatment on the bamboo fiber surface to form a chemical bond connection, which can be expressed as: bamboo fiber-OH + polyethylene grafted maleic anhydride (double bond opened) → bamboo fiber-O-grafted product.The isocyanate group (-NCO) in 1,6-hexamethylene diisocyanate has high reactivity and can react with the hydroxyl groups on the surface of bamboo fiber and the active functional groups in raw materials such as polyethylene grafted maleic anhydride. For example, it reacts with hydroxyl groups to form a carbamate bond: -NCO + OH → -NHCOO-. Through such a reaction, cross-linking between the raw materials is achieved, thereby enhancing the structural stability and performance of bamboo fiber.

[0016] Preferably, the filler is at least one of silicon dioxide, calcium carbonate, diatomaceous earth, kaolin, artificial talc, and hydrated magnesium silicate.

[0017] The present invention also provides a method for preparing a smooth and degradable PETG film, comprising the following steps: S1. According to parts by weight, the biodegradable polyester, PETG slices, compatible dispersant, toughening agent and plasticizer are added to a mixer and mixed for 10-20 minutes, and then toluene diisocyanate and modified bamboo fiber are added and mixed and stirred for 20-40 minutes to obtain a mixture A for standby use; S2. Add the lubricant according to weight to the mixture A, heat to 30-60° C. and stir for 20-40 min to obtain a mixture B for later use; S3, feed the mixture B through a twin-screw extruder, feed the filler through the side, and blend and granulate; wherein the temperature of the twin-screw extruder is set as follows: zone 1: 190±5℃; zone 2: 200±10℃; zone 3: 220±10℃; zone 4: 220±10℃; die head temperature: 220±10℃; screw speed of 300-380r / min; extrude and granulate to obtain degradable polyester particles for standby use; S4. Take the PVC film as the outer layer, melt the degradable polyester particles to obtain the degradable polyester coating, cast the degradable polyester coating on the surface of the PVC film to form a film body, and then stick the release paper on the surface of the film body to obtain a smooth and degradable PETG film.

[0018] The smooth and degradable PETG film of the present invention is prepared by the above method, and the degradable PETG film prepared by the above method overcomes the defects of existing products and also has good biodegradability, good mechanical properties, good optical properties and good light aging resistance.

[0019] The required film structure is formed by hot coating the biodegradable polyester coating on the film body. During the hot coating process, the various raw materials in the coating fuse with each other and are evenly distributed under the heat, and form a continuous and stable film layer after cooling, which together with the outer layer and the inner layer constitute a complete film; the properties of the film are regulated by using the characteristics of different raw materials. For example, toughening agents can enhance the toughness of the film to prevent it from easily breaking during use; plasticizers can improve the flexibility of the film, making it easier to process and adapt to different use environments.

[0020] The beneficial effects of the present invention are as follows: the degradable PETG film of the present invention overcomes the defects of existing products and also has good biodegradability, good mechanical properties, good optical properties and good light aging resistance; the film body adopts a degradable polyester coating, so that the effect of the sheet obtained when the thickness of the PETG slice layer in the composite sheet is 8.3-16.1% can achieve the heat sealing performance and low-temperature processing effect of the sheet obtained when the thickness of the PETG slice layer is about 20%, thereby reducing the amount of PETG slices used and greatly reducing the production cost.

[0021] The method for preparing the smooth and degradable PETG film is simple and convenient, has low requirements on production equipment, is low in cost, is conducive to industrial production, and can effectively overcome the shortcomings of previous lithium ion batteries. DETAILED DESCRIPTION

[0022] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with embodiments, and the contents mentioned in the implementation modes are not intended to limit the present invention. Example 1

[0023] A smooth and degradable PETG film comprises an outer layer, a film body and an inner layer which are arranged in sequence, wherein the film body is formed by thermal coating of a degradable polyester coating; the degradable polyester coating comprises the following raw materials in parts by weight: 40 parts of degradable polyester, 20 parts of PETG slices, 3 parts of a compatible dispersant, 4 parts of a toughening agent, 5 parts of a plasticizer, 4 parts of a smoothing agent, 10 parts of modified bamboo fibers, 5 parts of a filler and 1 part of toluene diisocyanate.

[0024] The degradable polyester is composed of polybutylene terephthalate succinate and polyglycolic acid in a mass ratio of 0.8:0.6.

[0025] The PETG slice is PETGCR-5511.

[0026] The compatible dispersant is maleic anhydride copolymer microspheres.

[0027] The toughening agent is composed of ethylene terephthalate, ethylene isophthalate, ethylene glycol, oxalic acid and stearate in a mass ratio of 3:0.1:1:1:0.04.

[0028] The plasticizer is epoxidized soybean oil.

[0029] The lubricant is erucamide.

[0030] The modified bamboo fiber comprises the following raw materials in parts by weight: 4 parts of phthalic acid type unsaturated polyester resin, 1 part of 1,6-hexamethylene diisocyanate, 30 parts of bamboo fiber, 5 parts of polyethylene grafted maleic anhydride, 1 part of graphene oxide, and 1 part of initiator; the initiator is N,N-dimethylaniline; The modified bamboo fiber is prepared by the following method: A1. Soak the bamboo fiber in a 1.0% by mass hydrogen peroxide solution, adjust the pH value of the solution to 10, soak for a period of time, and then put it into a blast drying oven to obtain alkaline hydrogen peroxide pretreated bamboo fiber for standby use; A2. According to the weight proportion, graphene oxide was prepared into a solution with a concentration of 0.1 mg / ml, and polyethylene grafted maleic anhydride, initiator and 1,6-hexamethylene diisocyanate were mixed evenly, and then bamboo fiber was added to the mixed system and stirred evenly, vacuum heated to 90°C, and pressurized to 3.0 MPa for 20 min, and finally transferred to a vacuum drying oven, heated to 130°C and dried for 3 h to obtain modified bamboo fiber.

[0031] The filler is silicon dioxide.

[0032] A method for preparing a smooth and degradable PETG film comprises the following steps: S1. According to parts by weight, the biodegradable polyester, PETG slices, compatible dispersant, toughening agent and plasticizer were added to a mixer and mixed for 10 minutes, and then toluene diisocyanate and modified bamboo fiber were added and mixed and stirred for 20 minutes to obtain a mixture A for standby use; S2. Add the lubricant according to weight to the mixture A, heat to 30° C. and stir for 40 min to obtain a mixture B for later use; S3, feed the mixture B through a twin-screw extruder, feed the filler through the side, and blend and granulate; wherein the temperature of the twin-screw extruder is set as follows: zone 1: 190±5°C; zone 2: 200±10°C; zone 3: 220±10°C; zone 4: 220±10°C; die head temperature: 220±10°C; screw speed is 300r / min; extrude and granulate to obtain degradable polyester particles for standby use; S4. Take the PVC film as the outer layer, melt the degradable polyester particles to obtain the degradable polyester coating, cast the degradable polyester coating on the surface of the PVC film to form a film body, and then stick the release paper on the surface of the film body to obtain a smooth and degradable PETG film. Example 2

[0033] A smooth and degradable PETG film comprises an outer layer, a film body and an inner layer which are arranged in sequence, wherein the film body is formed by thermal coating of a degradable polyester coating; the degradable polyester coating comprises the following raw materials in parts by weight: 50 parts of degradable polyester, 30 parts of PETG slices, 5 parts of a compatible dispersant, 6 parts of a toughening agent, 8 parts of a plasticizer, 6 parts of a smoothing agent, 15 parts of modified bamboo fibers, 8 parts of a filler and 3 parts of toluene diisocyanate.

[0034] The degradable polyester is composed of polybutylene terephthalate adipate and polylactic acid in a mass ratio of 1.0:0.8.

[0035] The PETG slice is PETG CR-5531.

[0036] The compatible dispersant is maleic anhydride copolymer microspheres.

[0037] The toughening agent is composed of ethylene terephthalate, ethylene isophthalate, ethylene glycol, oxalic acid and stearate in a mass ratio of 4:0.2:2:2:0.06.

[0038] The plasticizer is pentaerythritol.

[0039] The lubricant is ethylene bisstearamide.

[0040] The modified bamboo fiber comprises the following raw materials in parts by weight: 6 parts of phthalic acid type unsaturated polyester resin, 3 parts of 1,6-hexamethylene diisocyanate, 45 parts of bamboo fiber, 8 parts of polyethylene grafted maleic anhydride, 3 parts of graphene oxide, and 2 parts of initiator; the initiator is N,N-dimethylaniline; The modified bamboo fiber is prepared by the following method: A1. Soak the bamboo fiber in a hydrogen peroxide solution having a mass fraction of 1.3%, adjust the pH value of the solution to 11, soak for a period of time, and then put it into a blast drying oven to obtain alkaline hydrogen peroxide pretreated bamboo fiber for standby use; A2. According to the weight proportion, graphene oxide was prepared into a solution with a concentration of 0.3 mg / ml, and then polyethylene grafted maleic anhydride, initiator and 1,6-hexamethylene diisocyanate were mixed evenly, and then bamboo fiber was added to the mixed system and stirred evenly, and vacuum heated to 100°C, and pressurized to 3.1 MPa for 30 minutes, and finally transferred to a vacuum drying oven, heated to 135°C and dried for 5 hours to obtain modified bamboo fiber.

[0041] The filler is calcium carbonate.

[0042] A method for preparing a smooth and degradable PETG film comprises the following steps: S1. According to parts by weight, degradable polyester, PETG slices, compatible dispersant, toughening agent and plasticizer were added to a mixer and mixed for 15 minutes, and then toluene diisocyanate and modified bamboo fiber were added and mixed and stirred for 30 minutes to obtain a mixture A for standby use; S2. Add the lubricant according to weight to the mixture A, heat to 45° C. and stir for 30 min to obtain a mixture B for later use; S3, feed the mixture B through a twin-screw extruder, feed the filler through the side, and blend and granulate; wherein the temperature of the twin-screw extruder is set as follows: zone 1: 190±5℃; zone 2: 200±10℃; zone 3: 220±10℃; zone 4: 220±10℃; die head temperature: 220±10℃; screw speed is 340r / min; extrude and granulate to obtain degradable polyester particles for standby use; S4. Take the PVC film as the outer layer, melt the degradable polyester particles to obtain the degradable polyester coating, cast the degradable polyester coating on the surface of the PVC film to form a film body, and then stick the release paper on the surface of the film body to obtain a smooth and degradable PETG film. Example 3

[0043] A smooth and degradable PETG film comprises an outer layer, a film body and an inner layer which are arranged in sequence, wherein the film body is formed by thermal coating of a degradable polyester coating; the degradable polyester coating comprises the following raw materials in parts by weight: 55 parts of degradable polyester, 35 parts of PETG slices, 6 parts of a compatible dispersant, 7 parts of a toughening agent, 9 parts of a plasticizer, 8 parts of a smoothing agent, 18 parts of modified bamboo fibers, 9 parts of a filler and 4 parts of toluene diisocyanate.

[0044] The degradable polyester is composed of polybutylene succinate-adipate and polyglycolide-lactide in a mass ratio of 1.1:0.9.

[0045] The PETG slice is PETGCR-5511.

[0046] The compatible dispersant is maleic anhydride copolymer microspheres.

[0047] The toughening agent is composed of ethylene terephthalate, ethylene isophthalate, ethylene glycol, oxalic acid and stearate in a mass ratio of 4:0.25:2.5:2.5:0.07.

[0048] The plasticizer is epoxidized soybean oil.

[0049] The lubricant is composed of erucamide, ethylene bisstearamide and ethylene-vinyl acetate copolymer in a mass ratio of 0.5:0.5:0.7.

[0050] The modified bamboo fiber comprises the following raw materials in parts by weight: 7 parts of phthalic acid type unsaturated polyester resin, 3 parts of 1,6-hexamethylene diisocyanate, 45 parts of bamboo fiber, 8 parts of polyethylene grafted maleic anhydride, 4 parts of graphene oxide, and 2 parts of initiator; the initiator is N,N-dimethylaniline; The modified bamboo fiber is prepared by the following method: A1. Soak the bamboo fiber in a hydrogen peroxide solution having a mass fraction of 1.3%, adjust the pH value of the solution to 11, soak for a period of time, and then put it into a blast drying oven to obtain alkaline hydrogen peroxide pretreated bamboo fiber for standby use; A2. According to the weight proportion, graphene oxide was prepared into a solution with a concentration of 0.3 mg / ml, and then polyethylene grafted maleic anhydride, initiator and 1,6-hexamethylene diisocyanate were mixed evenly, and then bamboo fiber was added to the mixed system and stirred evenly, and vacuum heated to 120°C, and pressurized to 3.1 MPa for 30 min, and finally transferred to a vacuum drying oven, heated to 138°C and dried for 4 h to obtain modified bamboo fiber.

[0051] The filler is diatomaceous earth.

[0052] A method for preparing a smooth and degradable PETG film comprises the following steps: S1. According to parts by weight, degradable polyester, PETG slices, compatible dispersant, toughening agent and plasticizer were added to a mixer and mixed for 18 minutes, and then toluene diisocyanate and modified bamboo fiber were added and mixed and stirred for 35 minutes to obtain a mixture A for standby use; S2. Add the lubricant according to weight to the mixture A, heat to 45° C. and stir for 30 min to obtain a mixture B for later use; S3, the mixture B is fed through a twin-screw extruder as the main feed, and the filler is fed through the side feed, and the mixture is blended and granulated; wherein the temperature of the twin-screw extruder is set as follows: zone 1: 190±5°C; zone 2: 200±10°C; zone 3: 220±10°C; zone 4: 220±10°C; die head temperature: 220±10°C; screw speed is 360r / min; extrusion and granulation to obtain degradable polyester particles for standby use; S4. Take the PVC film as the outer layer, melt the degradable polyester particles to obtain the degradable polyester coating, cast the degradable polyester coating on the surface of the PVC film to form a film body, and then stick the release paper on the surface of the film body to obtain a smooth and degradable PETG film. Example 4

[0053] A smooth and degradable PETG film comprises an outer layer, a film body and an inner layer which are arranged in sequence, wherein the film body is formed by thermal coating of a degradable polyester coating; the degradable polyester coating comprises the following raw materials in parts by weight: 60 parts of degradable polyester, 40 parts of PETG slices, 7 parts of a compatible dispersant, 8 parts of a toughening agent, 10 parts of a plasticizer, 10 parts of a smoothing agent, 20 parts of modified bamboo fibers, 10 parts of a filler and 5 parts of toluene diisocyanate.

[0054] The degradable polyester is composed of poly(butylene adipate-co-butylene 2,5-furandicarboxylate) and poly(glycolide-caprolactone) in a mass ratio of 1.2:10.

[0055] The PETG slice is PETG CR-5531.

[0056] The compatible dispersant is maleic anhydride copolymer microspheres.

[0057] The toughening agent is composed of ethylene terephthalate, ethylene isophthalate, ethylene glycol, oxalic acid and stearate in a mass ratio of 5:0.1:1:3:0.08.

[0058] The plasticizer is epoxidized soybean oil.

[0059] The lubricant is ethylene bisstearamide.

[0060] The modified bamboo fiber comprises the following raw materials in parts by weight: 8 parts of phthalic acid type unsaturated polyester resin, 3 parts of 1,6-hexamethylene diisocyanate, 45 parts of bamboo fiber, 8 parts of polyethylene grafted maleic anhydride, 3 parts of graphene oxide, and 2 parts of initiator; the initiator is N,N-dimethylaniline; The modified bamboo fiber is prepared by the following method: A1. Soak the bamboo fiber in a 1.3% by mass hydrogen peroxide solution, adjust the pH value of the solution to 12, soak for a period of time, and then put it into a blast drying oven to obtain alkaline hydrogen peroxide pretreated bamboo fiber for standby use; A2. According to parts by weight, graphene oxide was prepared into a solution with a concentration of 0.4 mg / ml, and polyethylene grafted maleic anhydride, initiator and 1,6-hexamethylene diisocyanate were mixed evenly, and then bamboo fiber was added to the mixed system and stirred evenly, vacuum heated to 140°C, and pressurized to 3.2 MPa for 20 minutes, and finally transferred to a vacuum drying oven, heated to 140°C and dried for 3 hours to obtain modified bamboo fiber.

[0061] The filler is hydrated magnesium silicate.

[0062] A method for preparing a smooth and degradable PETG film comprises the following steps: S1. According to parts by weight, degradable polyester, PETG slices, compatible dispersant, toughening agent and plasticizer were added to a mixer and mixed for 20 minutes, and then toluene diisocyanate and modified bamboo fiber were added and mixed and stirred for 40 minutes to obtain a mixture A for standby use; S2. Add the lubricant according to weight to the mixture A, heat to 60° C. and stir for 20 min to obtain a mixture B for later use; S3, feed the mixture B through a twin-screw extruder, feed the filler through the side, and blend and granulate; wherein the temperature of the twin-screw extruder is set as follows: zone 1: 190±5℃; zone 2: 200±10℃; zone 3: 220±10℃; zone 4: 220±10℃; die head temperature: 220±10℃; screw speed is 380r / min; extrude and granulate to obtain degradable polyester particles for standby use; S4. Take the PVC film as the outer layer, melt the degradable polyester particles to obtain the degradable polyester coating, cast the degradable polyester coating on the surface of the PVC film to form a film body, and then stick the release paper on the surface of the film body to obtain a smooth and degradable PETG film.

[0063] The difference between this comparative example and the above-mentioned Example 3 is that no lubricant is added to the raw materials of the degradable polyester coating of this comparative example. The rest of the contents of this comparative example are the same as those of Example 3 and will not be repeated here.

[0064] The difference between this comparative example and the above-mentioned Example 3 is that no degradable polyester is added to the raw materials of the degradable polyester coating of this comparative example. The rest of the contents of this comparative example are the same as those of Example 3 and will not be repeated here.

[0065] The difference between this comparative example and the above-mentioned Example 3 is that conventional bamboo fiber is used in the raw material of the degradable polyester coating of this comparative example instead of modified bamboo fiber, and the remaining raw materials are mixed according to the proportions of Example 3. The rest of the contents of this comparative example are the same as those of Example 3 and will not be repeated here.

[0066] The degradable polyester coatings prepared in Example 3 and Comparative Example 1 were melt-cast onto the surface of a PVC film and cooled to obtain samples for performance testing. The results are shown in Table 1 below: Degradability: Biodegradability test is carried out according to GB / T 19277-2003 standard; Slipperiness: Biodegradability test is carried out in accordance with GBT10006-2021 standard; Mechanical properties: Tensile strength is tested in accordance with GB / T1040.3; Light transmittance: According to GB / T2410-2008, sample size is 100×100×2mm.

[0067] Table 1 project Biodegradability % Friction coefficient μ Tensile strength MPa Transmittance% Example 3 95.6 0.312 65.8 92 Example 1 94.7 0.536 65.4 93 The degradable polyester coatings prepared in Example 3 and Comparative Example 2 were melt-cast onto the surface of a PVC film and cooled to obtain samples for performance testing. The results are shown in Table 2 below: Degradability: Biodegradability test is carried out in accordance with GB / T 19277-2003 standard.

[0068] Table 2 project Biodegradability % Example 3 95.6 Comparative Example 2 65.7 The degradable polyester coatings prepared in Example 3 and Comparative Example 3 were melt-cast onto the surface of a PVC film and cooled to obtain samples for performance testing. The results are shown in Table 3 below: Degradability: Biodegradability test is carried out according to GB / T 19277-2003 standard; Mechanical properties: The tensile strength is tested in accordance with GB / T1040.3.

[0069] Table 3 project Biodegradability % Tensile strength MPa Example 3 95.6 65.8 Comparative Example 1 86.3 52.7 It can be seen from the data in Tables 1-3 that the degradable polyester coating prepared in Example 3 of the present invention has excellent light transmittance, which can reach more than 90%, and also has good mechanical properties, slippery properties and degradable properties. By adding a slip agent, a degradable polyester and modified bamboo fiber to the raw materials for preparing the degradable polyester coating, the problems existing in the current degradable composite PETG film are fundamentally solved.

[0070] The above embodiments are preferred implementation schemes of the present invention. In addition, the present invention may also be implemented in other ways. Any obvious replacement without departing from the concept of the present invention is within the protection scope of the present invention.

Claims

1. A smooth and degradable PETG film, characterized in that: It comprises an outer layer, a film body and an inner layer which are arranged in sequence, wherein the film body is formed by thermal coating of a degradable polyester coating; the degradable polyester coating comprises the following raw materials in parts by weight: 40-60 parts of degradable polyester, 20-40 parts of PETG slices, 3-7 parts of a compatible dispersant, 4-8 parts of a toughening agent, 5-10 parts of a plasticizer, 4-10 parts of a lubricant, 10-20 parts of modified bamboo fibers, 5-10 parts of a filler and 1-5 parts of toluene diisocyanate.

2. A smooth and degradable PETG film according to claim 1, characterized in that: The degradable polyester is composed of at least one of polybutylene terephthalate succinate, polybutylene terephthalate adipate, polybutylene succinate-adipate, poly(butylene adipate-co-butylene 2,5-furandicarboxylate), poly(butylene succinate-co-butylene 2,5-furandicarboxylate) and polybutylene succinate-polylactic acid and at least one of polyglycolic acid, polylactic acid, polyglycolide-lactide and polyglycolide-caprolactone in a mass ratio of 0.8-1.2:0.6-10.

3. A smooth and degradable PETG film according to claim 1, characterized in that: The PETG slices are one or a mixture of PETGCR-5511 and PETG CR-5531.

4. A smooth and degradable PETG film according to claim 1, characterized in that: The toughening agent is composed of ethylene terephthalate, ethylene isophthalate, ethylene glycol, oxalic acid and stearate in a mass ratio of 3-5:0.1-0.3:1-3:1-3:0.04-0.

08.

5. The smooth and degradable PETG film according to claim 1, characterized in that: The plasticizer is epoxidized soybean oil and / or pentaerythritol.

6. The smooth and degradable PETG film according to claim 1, characterized in that: The lubricant is at least one of erucic acid amide, ethylene bis stearamide, silica open lubricant masterbatch, paraffin, ethylene-vinyl acetate copolymer, and ethylene-acrylic acid copolymer.

7. The smooth and degradable PETG film according to claim 1, characterized in that: The modified bamboo fiber comprises the following raw materials in parts by weight: 4-8 parts of phthalic acid type unsaturated polyester resin, 1-5 parts of 1,6-hexamethylene diisocyanate, 30-60 parts of bamboo fiber, 5-10 parts of polyethylene grafted maleic anhydride, 1-5 parts of graphene oxide, and 1-3 parts of initiator.

8. The smooth and degradable PETG film according to claim 7, characterized in that: The modified bamboo fiber is prepared by the following method: A1. Soak the bamboo fiber in a hydrogen peroxide solution with a mass fraction of 1.0-1.5%, adjust the pH value of the solution to 10-12, soak for a period of time, and then put it into a blast drying oven to obtain alkaline hydrogen peroxide pretreated bamboo fiber for standby use; A2. According to parts by weight, graphene oxide is prepared into a solution with a concentration of 0.1-0.4 mg / ml, and then polyethylene grafted maleic anhydride, initiator and 1,6-hexamethylene diisocyanate are mixed evenly, and then bamboo fiber is added to the mixed system and stirred evenly, vacuum heated to 90-140°C, and pressurized to 3.0-3.2 MPa, treated for 20-40 minutes, and finally transferred to a vacuum drying oven, heated to 130-140°C and dried for 3-7 hours to obtain modified bamboo fiber.

9. The smooth and degradable PETG film according to claim 1, characterized in that: The filler is at least one of silicon dioxide, calcium carbonate, diatomaceous earth, kaolin, artificial talc and hydrated magnesium silicate.

10. A method for preparing the smooth and degradable PETG film according to any one of claims 1 to 9, characterized in that: The steps include: S1. According to parts by weight, the biodegradable polyester, PETG slices, compatible dispersant, toughening agent and plasticizer are added to a mixer and mixed for 10-20 minutes, and then toluene diisocyanate and modified bamboo fiber are added and mixed and stirred for 20-40 minutes to obtain a mixture A for standby use; S2. Add the lubricant according to weight to the mixture A, heat to 30-60° C. and stir for 20-40 min to obtain a mixture B for later use; S3, feed the mixture B through a twin-screw extruder, feed the filler through the side, and blend and granulate; wherein the temperature of the twin-screw extruder is set as follows: zone 1: 190±5℃; zone 2: 200±10℃; zone 3: 220±10℃; zone 4: 220±10℃; die head temperature: 220±10℃; screw speed of 300-380r / min; extrude and granulate to obtain degradable polyester particles for standby use; S4. Take the PVC film as the outer layer, melt the degradable polyester particles to obtain the degradable polyester coating, cast the degradable polyester coating on the surface of the PVC film to form a film body, and then stick the release paper on the surface of the film body to obtain a smooth and degradable PETG film.